Observed what tipping bidet only can reveal (5)
I believe the answer is:
noted
'observed' is the definition.
('note' can be a synonym of 'observe')
'tipping bidet only can reveal' is the wordplay.
'tipping' says the letters should be written backwards.
'reveal' indicates a hidden word.
'deton' is hidden within 'bidet only can'.
'deton' back-to-front is 'NOTED'.
'what' acts as a link.
(Other definitions for noted that I've seen before include "Wrote it down" , "Scored" , "Celebrated or recorded" , "Made a record - celebrated" , "Famous or eminent" .)